Heat-resistant resin compositions, and heat-resistant molded or formed articles and production process thereof

ABSTRACT

Heat-resistant resin composition including (A) 100 parts by weight of a poly(arylene sulfide) of a substantially linear structure containing 50% by weight or higher or recurring units of the formula ##STR1## and a logarithmic viscosity number of 0.1 to 1.0 dl/g; (B) from 0.01 to less than 25 parts by weight of a melt-stable poly(arylene thioether-ketone) having predominant recurring units of the formula ##STR2## wherein the --CO-- and --S-- are in the para position to each other, and having a melting point of 310°-380° C., a residual melt crystallization enthalpy of at least 10 J/g, a melt crystallization temperature of at least 210° C. and a reduced viscosity of 0.2 to 2 dl/g; and (C) at least one of fibrous fibers and/or at least one of inorganic fillers in a proportion of 0 to 400 parts by weight per 100 parts by weight of the resin component including said poly(arylene sulfide) and said poly(arylene thioether-ketone). Heat-resistant articles obtained by melt-molding or forming said resin compositions and a method for the production of such articles are also described.

This is a division of application Ser. No. 07/194,016, filed 5/12/88,now U.S. Pat. No. 4,895,893.

FIELD OF THE INVENTION

The present invention relates to a melt-moldable or formablepoly(arylene sulfide) resin composition having heat-, oil- and wetheat-resistance as well as low gas permeability and its molded or formedarticle, and more particularly to a resin composition obtained by mixinga poly(arylene sulfide) having a substantially linear structure(hereinafter abbreviated as "PAS") with a melt-stable poly(arylenethioether-ketone) (hereinafter abbreviated as "PTK") and optionally, atleast one of fibrous fillers and/or at least one of inorganic fillers, aheat resistant article obtained by melt-molding or forming said resincomposition and a method for producing the same.

BACKGROUND OF THE INVENTION

In recent years, there has been an increasing demand for crystallinethermoplastic, heat-resistant and easily melt-processable resins inautomotive, electronic and electric industries. For instance, with thespread of electronic ranges, electrical ovens and electronic oven/rangecombinations in domestic electrical fields, heat-resistant andelectromagnetic wave-transmitting containers for foodstuffs have beenmuch in demand. For that reason, attention has now been paid toeasy-to-crystallize polyethylene terephthalate (hereinafter abbreviatedas "PET") as a material capable of molding or forming heat-resistantplastic containers, e.g., thermoformed food containers which may be usedwith domestic electronic ranges, electrical ovens, etc. and can stand upto an oven temperature close to 200° C.

However, PET containers may be used in applications where relativelyshort-time heating meets the purpose, as is the case with electronicranges, but are disadvantageous in that they are still so poor in heatresistance that they cannot withstand a high temperature of 200° C. orhigher, inter alia, 220° to 230° C., in electronic ranges or electricalovens.

Thermosetting resins such as unsaturated polyester resins or epoxyresins are moldable by the sheet molding compound (SMC) or bulk moldingcompound (BMC) system, and may be molded into food containers. The SMCis a sheet-like intermediate material for press molding obtained byimpregnating in matted glass fibers a resin paste prepared by mixing athermosetting resin with a filler, catalyst (a curing initiator),releasing agent, chemical thickener and the like. This sheet-likematerial is stored at a given temperature for a given period of time,and is designed to be molded or formed by a press at the time when theresin is semi-set or dried to the touch under the action of thethickener. The BMC is prepared by kneading together with glass fibers(chopped strands) a resin paste wherein a thermosetting resin is blendedwith a filler, chemical thickener, catalyst (a curing initiator),pigment, releasing agent and the like. The BMC may be molded by pressmolding, transfer molding, injection molding and the like.Heat-resistant food containers may be produced from thermosetting resinsby such molding processes. However, food containers formed ofthermosetting resins such as unsaturated polyesters are disadvantageousin that they cannot stand up to high temperatures prevailing inelectronic ranges or electrical ovens due to their heat-resistanttemperature being as low as about 210° C.

On the other hand, engineering plastics such as poly(arylene sulfide)(PAS) and poly(arylene thioether-ketone) (PTK) are now being developedor in practical use as thermoplastic resins excellent in heatresistance.

PAS is a thermoplastic resin used in wide fields as the engineeringplastics showing excellent resistance to heat, chemicals (acids,alkalis, solvents), oils and hot water, good processability and havingexcellent mechanical properties. Taking advantage of its excellentproperties, PAS is also used in the form of films or fibers. PAS is acrystalline resin, and is better in heat resistance than PET due to itsmelting point higher than that of PET. PAS is also excellent in theresistance to wet heat, solvents, etc.

There are some disclosures on PTK, for instance, GermanOffenlegungsschrift 34 05 523 A1, Japanese Patent Laid-Open PublicationNos. 58435/1985, 104126/1985 and 13347/1972, Indian J. Chem., 21A, pp.501-502 (May, 1982), and Japanese Patent Laid-Open Publication No.221229/1986. With the conventional PTK described in such publications,however, difficulty was encountered in melt molding by conventional meltmolding/forming processes such as injection molding or extrusion, sinceit was so poor in melt stability that it lost its crystallinity orunderwent a curing reaction with increases in melting viscosity duringmelt processing.

However, it has been found that PTK improved highly over theconventional PTK in melt stability are obtained by modifying thepolymerization procedures, i.e., carrying out polymerization withoutadding any polymerization aid while taking into consideration theselection of a charge ratio of monomers, a shorter polymerization timeat high temperatures, the selection of the material of the reactor usedand the like and, optionally, conducting a stabilization treatment in afinal stage of the polymerization. Such PTK is melt stable and moldableor formable by conventional melt processing (Japanese Patent ApplicationNo. 62-118619).

Incidentally, U.S. Pat. No. 4,690,972 specification discloses that PTKis added to PAS as a nucleating agent. However, said PTK is differentfrom the said melt-stable PTK, and nowhere in that specification areheat-resistant molded or formed articles such as heat-resistant foodcontainers disclosed.

The present inventors have made intensive studies so as to obtainheat-resistant compositions and molded or formed articles, takingadvantage of the properties of PAS and melt-stable PTK as mentionedabove.

In consequence, it has been found that a heat-resistant container isobtained by melt-molding or forming the melt-stable PTK alone or athermoplastic material obtained by mixing 100 parts by weight of athermoplastic resin such as PAS with said PTK in an amount of 25 partsby weight or more (Japanese Patent Application No. 195806/1987). Thisapproach has however been found to involve problems such that a highmelting-point PTK or a PTK-PAS composition containing the PTK in a largeproportion requires a high-temperature mold in order to obtain a moldedarticle excellent in surface characteristics and the resultant moldedarticle is expensive due to the abundant use of the PTK more expensivecompared to PAS.

OBJECTS AND SUMMARY OF THE INVENTION

An object of the present invention is to provide a heat-resistantcomposition and a heat-resistant molded or formed article, whichovercome the drawbacks of the prior art.

Another object of the present invention is to obtain a heat-resistantmolded or formed article whose thickness and filler content can becontrolled freely by melt molding or forming. It is herein understoodthat the term "heat-resistant molded or formed article" is intended toinclude articles obtained by conventional processing techniques such asextrusion, injection molding, vacuum forming, stretched film forming,stretched sheet forming, electric part encapsulation and melt spinning.

A further object of the present invention is to obtain a heat-resistantfood container.

The present inventors have found that a resin composition excellent inheat resistance is obtained by mixing 100 parts by weight of apoly(arylene sulfide) (PAS) of a substantially linear structurecontaining 50% by weight or higher of recurring units of the formula:##STR3## and having a logarithmic viscosity number of 0.1 to 1.0 dl/g ina 1-chloronaphthalene solution as measured at a polymer concentration of0.4 g/dl and a temperature of 208° C. with from 0.01 to less than 25parts by weight of a melt-stable poly(arylene thioether-ketone (PTK) andoptionally, 0 to 400 parts by weight of at least one of fibrous fillersand/or at least one of inorganic fillers, and a molded or formed articleexcellent in heat resistance, oil resistance and wet heat resistance andhaving low gas permeability is obtained by melt-molding or forming saidresin composition. Such findings underlie the present invention.

More specifically, according to one aspect of the present invention,there is provided a resin composition comprising:

(A) 100 parts by weight of a poly(arylene sulfide) of a substantiallylinear structure containing 50% by weight or higher of recurring unitsof the formula: ##STR4## and having a logarithmic viscosity number of0.1 to 1.0 dl/g in a 1-chloronaphthalene solution at a polymerconcentration of 0.4 g/dl and a temperature of 208° C.;

(B) from 0.01 to less than 25 parts by weight of a melt-stablepoly(arylene thioether-ketone) having predominant recurring units of theformula: ##STR5## wherein the --CO-- and --S-- are in the para positionto each other, and having the following physical properties (a)-(c):

(a) melting point, Tm being 310°-380° C.;

(b) residual melt crystallization enthalpy, ΔHmc (420° C./10 min) beingat least 10 J/g, and melt crystallization temperature, Tmc (420° C./10min) being at least 210° C., wherein ΔHmc (420° C./10 min) and Tmc (420°C./10 min) are determined by a differential scanning calorimeter at acooling rate of 10° C./min, after poly(arylene thioether-ketone) is heldat 50° C. for 5 minutes in an inert gas atmosphere, heated to 420° C. ata rate of 75° C./min, and then held at 420° C. for 10 minutes; and

(c) reduced viscosity being 0.2-2 dl/g as determined by viscositymeasurement at 25° C. and a polymer concentration of 0.5 g/dl in 98 wt.% sulfuric acid; and

(C) at least one of fibrous fillers and/or at least one of inorganicfillers in a proportion of 0 to 400 parts by weight per 100 parts byweight of the resin component comprising said poly(arylene sulfide) andsaid poly(arylene thioether-ketone).

According to another aspect of the present invention, there is provideda heat-resistant molded or formed article obtained by melt-molding orforming said resin composition.

According to a further aspect of this invention, there is provided amethod for the production of a heat-resistant molded articlecharacterized by injection-molding said resin composition under theconditions of a cylinder temperature of 270° to 400° C., a moldtemperature of 50° to 250° C., an injection holding pressure of 10 to5000 kg/cm² and an injection cycle of 1 to 600 seconds and optionally,an annealing temperature of 120° to 250° C. for 10 to 600 minutes.

DETAILED DESCRIPTION OF THE INVENTION Components of Resin Compositions(PAS)

The PAS used in the present invention is a poly(arylene sulfide) of asubstantially linear structure, which contains 50% by weight or more,preferably 70% by weight or more, more preferably 90% by weight or moreof recurring units of p-phenylene sulfide: ##STR6## as predominantrecurring units of the polymer.

It is herein understood that the "substantially linear structure" refersto polymers obtained from monomers composed mainly of substantiallybifunctional monomers, rather than polymers having a crosslinked andbranched structure such as those obtained by a melt-viscosity increasingtreatment such as oxidation crosslinking.

Corresponding to 50% by weight or more of the p-phenylene sulfiderecurring units, the PAS may contain less than 50% by weight of otherconstituent units.

By way of example, such constituent units may include a metaphenylenesulfide unit of the formula ##STR7## a diphenylenesulfone sulfide unitof the formula ##STR8## a diphenyl sulfide unit of the formula ##STR9##a diphenyl ether sulfide unit of the formula ##STR10## a 2,6-naphthalenesulfide unit of the formula ##STR11## and a trifunctional unit of theformula ##STR12##

It is noted that the amount of trifunctional (tetra- or more-functional)units should preferably be not more than 1 mol %.

PAS having a high solution viscosity and a high degree of polymerizationmay be producing by the method described in, e.g., U.S. Pat. No.4,645,826.

The method for the production of the PAS as described in U.S. Pat. No.4,645,826 is to produce poly(arylene sulfides) having a melt viscosityof 1000 poise or higher (it should be noted, however, that the meltviscosity referred to in the present invention was measured at 310° C.and a shear rate of 200/sec), and involves the reaction of an alkalimetal sulfide with a dihalo-aromatic compound in an organic amidesolvent, which takes place at least two steps of:

(1) carrying out said reaction at a temperature of 180° to 235° C. inthe presence of water in a proportion of 0.5 to 2.4 moles per mole ofsaid alkali metal sulfide, thereby forming a poly(arylene sulfide)having a melt viscosity of 5 to 300 poise at a conversion of 50 to 98mol % with respect to said dihalo-aromatic compound, and

(2) continuing said reaction, while adding water to the reaction systemin such a way that 2.5 to 7.0 moles of water is present per mole of saidalkali metal sulfide and increasing the temperature of the reactionsystem to the range of 245° to 290° C.

Use may preferably be made of block copolymers composed mainly of thep-phenylene sulfide recurring units of the formula ##STR13## forinstance, block copolymers containing 70 to 95 mole % of recurring unitsof the formula ##STR14## and 5 to 30 mole % of metaphenylene sulfiderecurring units of the formula ##STR15## Such block copolymers having ahigh melt viscosity may be produced by the method described in, e.g.,EPC No. 166451-A.

The PAS used in the present invention is of the chemical structure asstated above, and has its solution viscosity expressed in terms of alogarithmic viscosity number of 0.1 to 1.0 dl/g, preferably 0.25 to 0.9dl/g in a 1-chloronaphthalene solution as measured at a polymerconcentration of 0.4 g/dl and a temperature of 208° C. A polymer havinga melt viscosity as low as a logarithmic viscosity number of below 0.1is unpreferred, since it may be melt-molded or formed, but the resultingproduct becomes mechanically fragile. On the other hand, a polymerhaving a logarithmic viscosity number exceeding 1.0 is again unpreferreddue to its poor processability.

In accordance with heat-resistant resin compositions and molded orformed articles of the present invention, the melt-stable PTK and,optionally at least one of fibrous fillers and/or at least one ofinorganic fillers are added to the PAS with a view tomodifying/improving the physical properties that the heat-resistantresin PAS possess (for instance, mechanical, electrical, thermal,chemical and like properties), modifying/improving the processabilitythereof and cutting down the cost thereof.

Melt-Stable PTK

The melt-stable PTK used in the present invention is a poly(arylenethioether-ketone) (PTK) having predominant recurring units of theformula ##STR16## wherein the --CO-- and --S-- are in the para positionto each other. In order to be a heat-resistant polymer, the PTK used inthe present invention should preferably contain said recurring units ina proportion of 50% by weight or higher, preferably 60% by weight orhigher and more preferably 70% by weight or higher. A polymer containingsaid recurring units in a proportion of below 50% by weight is likely tobe low in crystallinity and hence has poor heat resistance.

Exemplary recurring units other than the above recurring units of theformula may include: ##STR17## (except for the recurring unit in whichthe --CO-- and --S-- are in the para position to each other.); ##STR18##(wherein R means an alkyl group having 5 or less carbon atoms and mstands for an integer of 0-4.).

It is desirable that the melt-stable PTKs employed in this invention areuncured polymers, especially, uncured linear polymers. The term "cure"as used herein means a molecular-weight increasing treatment by a methodother than a usual polycondensation reaction, for example, by acrosslinking, branching or molecular-chain extending reaction,particularly, a molecular-weight increasing treatment by ahigh-temperature heat treatment or the like. By the term "uncuredpolymer" as used herein, is meant a polymer which has not been subjectedto a post treatment such that curing is applied to increase themolecular weight of the polymer and hence to increase its meltviscosity. In general, "curing" causes a PTK to lose or decrease itsmelt stability and crystallinity.

PTK, into which some crosslinked and/or branched structure is introducedwithin such limits that its melt stability, flowability andcrystallinity are not degraded, may be used as the blending resin in thepresent invention. For instance, a PTK obtained by carrying outpolymerization with the use of a small amount of a crosslinking agent(e.g., polychlorobenzophenone, polybromobenzophenone or the like) or aPTK subjected to mild curing are allowable as PTK used in the presentinvention.

Physical Properties of PTK

The PTK used in the present invention should preferably possess thefollowing physical properties.

(a) The melting point, Tm should range from 310° to 380° C.

(b) The residual melt crystallization enthalpy, ΔHmc (420° C./10 min)should be at least 10 J/g, and the melt crystallization temperature, Tmc(420° C./10 min) should be at least 210° C.

(c) The reduced viscosity, η_(red) should be 0.2 to 2 dl/g. In thepresent invention, it is understood that the reduced viscosity, η_(red)is expressed in terms of a value as measured at 25° C. and a polymerconcentration of 0.5 g/dl in 98 wt. % sulfuric acid.

(d) As an index indicating the properties of crystallinity, the densityin the crystallized form when PTK is annealed at 280° C. for 30 minutesshould be at least 1.34 g/cm³ (at 25° C.). A PTK having a reducedviscosity exceeding 2 dl/g is difficult to be prepared or melt molded,while a PTK having a reduced viscosity of below 0.2 dl/g is unpreferred,since it is likely that the mechanical properties of compositions of thePAS mixed with such PTK are poor.

The properties of the PTK used in the present invention will bedescribed in more detail.

(1) Heat Resistance

The melting point, Tm serves as an index of the heat resistance of apolymer.

The PTK used in the present invention has a melting point, Tm of 310° to380° C., preferably 320° to 375° C., more preferably 330° to 370° C. PTKhaving a Tm of below 310° C. is unpreferred due to its insufficient heatresistance, while the PTK having a Tm exceeding 380° C. is undesiredsince difficulty is experienced in melt-processing it withoutdecomposition.

(2) Melt Stability

The greatest feature of the PTK resin used in the present invention isthat it has a melt stability sufficient to permit the application ofconventional melt processing techniques.

The conventional PTK are all poor in melt stability, so that they tendto decrease in flowability or lose their crystallinity or to undergocrosslinking or carbonization, resulting an abrupt increase in meltviscosity during melt processing.

It is hence possible to obtain an index of the melt processability ofthe PTK by investigating the residual crystallinity of the PTK afterholding it at a temperature equal to or higher than the melt processingtemperature for a certain period of time. The residual crystallinity canbe evaluated quantitatively in terms of melt crystallization enthalpy.Specifically, the residual melt crystallization enthalpy, ΔHmc (420°C./10 min) and melt crystallization temperature, Tmc (420° C./10 min)are determined by a differential scanning calorimeter at a cooling rateof 10° C./min after the PTK is held at 50° C. for 5 minutes in an inertgas atmosphere, heated to 420° C. at a rate of 75° C./min, and then heldat 420° C. for 10 minutes. PTK, poor in melt stability, undergoescrosslinking or the like under the above high-temperature condition of420° C. and loses its crystallinity substantially.

The melt-stable PTK used in the present invention is a polymer which hasa ΔHmc (420° C./10 min) of at least 10 J/g, more preferably at least 15J/g, most preferably at least 20 J/g and a Tmc (420° C./10 min) of atleast 210° C., more preferably at least 220° C., most preferably 230° C.

PTK having a ΔHmc (420° C./10 min) of lower than 10 J/g or a Tmc (420°C./10 min) of below 210° C. tends to lose its crystallinity or induces amelt viscosity increase during melt processing, so that difficulty isencountered in the application of conventional melt processingtechniques.

(3) Molecular Weight

The molecular weight of the PTK correlating with the melt viscosity isan important factor which governs its melt processability. Reducedviscosity, η_(red) is used as an index of molecular weight.

It is desired that the PTK suitable for melt processing be ahigh-molecular weight PTK having a reduced viscosity, η_(red) of 0.2 to2 dl/g, more preferably 0.3 to 2 dl/g, most preferably 0.5 to 2 dl/g.

(4) Crystallinity

Density is used as an index of crystallinity of a polymer.

It is desired that the PTK used in the present invention be a polymerhaving a density at 25° C. of at least 1.34 g/cm³, more preferably atleast 1.35 g/cm³, as measured in the crystallized form by annealing itat 280° C. for 30 minutes. In the case of PTK having a density of below1.34 g/cm³, it is likely that its heat resistance may be insufficientdue to its low crystallinity, and the physical properties of molded orformed articles obtained from the PAS resin compositions containing itmay drop.

Production Process of the PTK

The PTK used in the present invention may be produced, for instance, bysubjecting an alkali metal sulfide and a dihalo-aromatic compound,preferably, dichlorobenzophenone and/or dibromobenzophenone to adehalogenation and sulfuration reaction, for a short period of time, inthe substantial absence of any polymerization aid (a slat of acarboxylic acid or the like), in an aprotic polar organic solvent,preferably, an organic amide solvent (including a carbamic amide or thelike) and in a system having a water content much higher compared withthe polymerization processes of the prior art while suitably controllingthe temperature, and optionally, by choosing the material of a reactor.

Specifically, the melt-stable PTK used in the present invention cansuitably be produced by polymerizing an alkali metal sulfide and adihalo-aromatic compound consisting principally of4,4'-dichlorobenzophenone and/or 4,4'-dibromobenzophenone by adehalogenation and sulfuration reaction under the following conditions(a)-(c) in an organic amide solvent:

(a) The ratio of the water content to the amount of the organic amidesolvent charged should be in a range of 2.5 to 15 (moles/kg);

(b) The ratio of the amount of the dihalo-aromatic compound charged tothe amount of the alkali metal sulfide charged should be in a range of0.95 to 1.2 (moles/moles); and

(c) The reaction should take place at a temperature ranging from 60° to300° C. with a proviso that the reaction time at 210° C. or higher belimited to within 10 hours.

The melt-stable PTK can more suitably be obtained, when the reactor, orat least a portion of which being brought into contact with the reactionmixture is made of a corrosion-resistant material such as a titaniummaterial.

The PTK having further improved melt stability can be obtained by addinga halogen-substituted aromatic compound to the alkali metal sulfide,said halogen-substituted aromatic compound has at least one substituentgroup having electron withdrawing property at least equal to a --CO--group (preferably 4,4'-dichlorobenzophenone and/or4,4'-dibromobenzophenone employed as the monomer) for further reactionin a final stage of the polymerization.

Proportion of the PTK to be Blended

The proportion of the melt-stable PTK to be used and blended with 100parts by weight of the PAS according to the present invention is from0.01 to less than 25 parts by weight, preferably 0.1 to 24 parts byweight. At an amount smaller than 0.01 part by weight, the PTK does notsufficiently function as the blending resin (or does not sufficientlytake advantage of its physical properties). Addition of more than 25parts by weight does not improve the nucleating effect so much comparedwith addition of less than 25 parts by weight. For good economy andeffect of the PTK an amount exceeding 25 parts by weight is notbeneficial.

When the PAS compositions wherein the proportion of the melt-stable PTKblended with the PAS falls within the scope of the present invention, itis possible to obtain the PAS molded or formed products suitable forvarious types of processing and excellent in heat resistance, sincetheir crystallization rate is increased, while a fine spherulithicstructure is formed.

Fibrous Filler and Inorganic Filler

Any fibrous fillers that can be incorporated into food containers areapplicable to the present invention, and may include fibers such asglass, carbon, graphite, silica, alumina, zirconia, silicon carbide andAramid fibers; as well as whiskers such as calcium silicate (includingwollastonite), calcium sulfate, carbon, silicon nitride and boronwhiskers, by way of example. Of these fibers, particular preference isgiven to glass fibers, carbon fibers and Aramid fibers from theviewpoints of physical properties. The inorganic fillers used mayinclude, e.g., talc, mica, kaolin, clay, silica, alumina,silica-alumina, titanium oxide, zirconium oxide, calcium carbonate,calcium silicate, calcium phosphate, calcium sulfate, magnesiumcarbonate, magnesium phosphate, carbon (including carbon black),graphite, silicon nitride, glass hydrotalcite, etc., all in the powderyform.

In the present invention, one or more of such fillers may be blended atneed. The fibrous fillers and inorganic fillers may be used alone or incombination.

The fibrous filler and/or inorganic filler used in the present inventionshould be blended in a proportion of 0 to 400 parts by weight,preferably 0.1 to 300 parts by weight, more preferably 1 to 200 parts byweight with respect to 100 parts by weight of the resin componentcomprising a mixture of PAS and the melt-stable PTK. The proportion ofthe filler or fillers exceeding 400 parts by weight is unpreferred,since there is a fear that processability may deteriorate. It isunderstood that a small amount of the filler or fillers tends to lowerthe heat distortion temperature of the molded or formed articles underload, as compared with those containing a larger amount of the filler orfillers.

The PAS resin compositions of the present invention may optionally beadded with auxiliary additives such as photostabilizers, rustpreventives, lubricants, surface-roughening agents, nucleating agents,releasing agents, colorants, coupling agents, flash preventives,antistatic agents and so on.

Molded or Formed Articles

Molded or formed articles obtainable from the PAS resin compositions ofthe present invention should possess the following physical properties(a)-(b).

(a) The heat distortion temperature, as measured under a load of 18.6kg/cm² according to ASTM D-648, should be at least 220° C., preferablyat least 230° C., more preferably at least 250° C.

(b) The flexural strength, as measured at 200° C. (according to ASTMD-790), should be at least 2 kg/mm², preferably at least 3 kg/mm², orthe flexural modulus, as measured at 200° C. (according to ASTM D-790),should be at least 100 kg/mm², preferably at least 150 kg/mm², morepreferably at least 200 kg/mm².

Since the molded articles of the present invention excel in heatresistance, and possess high mechanical strength, satisfactory chemicalresistance and hot water resistance and low gas permeability, they arevaluable in various application fields inclusive of industrial, medical,foodstuff and general goods fields where heat resistance is required.

When molded articles having a heat distortion temperature of below 220°C., a flexural strength of below 2 kg/mm² at 200° C. and a flexuralmodulus of below 100 kg/mm² at 200° C. are used for food containers, byway of example, there is a fear that they may be deformed either in thecourse of cooking in an electronic oven range or on their removal afterthe completion of cooling.

The resin compositions of the present invention can be molded or formedinto from thin- to thick-walled containers for foodstuffs, usually inthe order of about 0.1 to 10 mm thick-walled containers.

Molding or Forming Method

The PAS resin compositions of the present invention may be molded orformed into articles by conventional melt processing (extrusion,injection molding, etc.). In particular, the PAS resin compositions ofthe present invention is preferably molded by injection molding in viewof facilitation. Alternatively, the resin compositions may be extrudedinto sheet-like or tubular articles or fibers, which are in turnsubjected to post-forming, stretching, crystallization and so on.

Injection Molding

The PAS resin composition of the present invention is supplied to aninjection molding machine provided with a mold for thin-walled articlesin the air or a non-oxidizing atmosphere, and is injection-molded underthe molding conditions of a cylinder temperature of 270° to 400° C.,preferably 290° to 360° C., a mold temperature of 50° to 250° C.,preferably 120° to 180° C. and an injection holding pressure of 10 to5000 kg/cm², preferably 50 to 3000 kg/cm² and an injection molding cycleof 1 to 600 seconds, preferably 3 to 120 seconds, optionally, followedby annealing at a temperature of 120° to 250° C., preferably 150° to210° C. for 10 to 600 minutes, preferably 20 to 240 minutes, whereby theheat-resistant molded article of the present invention can be produced.

Cylinder temperatures lower than 270° C. or higher than 400° C. areunpreferred, since the lower temperatures make the flow of the resincompositions difficult, while the higher temperatures tend to cause thethermal decomposition of the resin compositions. Mold temperatures lowerthan 50° C. or higher than 250° C. are unpreferred, since the lowertemperatures tend to cause the molded articles to be roughened on theirsurfaces, while the higher temperatures make the solidification of themolded articles difficult. Injection holding pressure lower than about10 kg/cm² are unpreferred, since the filling of the resin in the moldtends to become incomplete. Excessively high injection holding pressuresare also unpreferred, since difficulty is experienced in reducing theflashing of the molded articles. An extremely short injection moldingcycle is unpreferred, since the solidification of the resin in the moldtends to become insufficient. An extremely long injection molding cycleis also unpreferred, since the residence time of the polymer in theinjection machine is so extended that the polymer may possibly bediscolored or degraded. If the mean residence time of the resin in thecylinder is below 1 second, then it is likely that the melting of theresin may become incomplete. If a residence time of resin in thecylinder exceeds 600 seconds, then it is likely that the resin may bedecomposed.

Preferably, the injection molding machine used in the present inventionhas its portion, in contact with a resin melt, formed of a nonferrouscorrosion-resistant material, and is provided with a vent.

The heat-resistant PAS resin compositions used in the present inventionmay be in the form of either powders or pellets. It is preferred,however, that they are in the form of pellets, since their steady supplyto the molding machine is facilitated.

Application Fields

The heat-resistant resin compositions and molded articles according tothe present invention may find use in wide application fields in whichheat resistance is demanded. In particular, the heat-resistant moldedarticles according to the present invention can suitably be used as foodcontainers for cooking with electronic ranges, electronic oven ranges,etc. Besides, they can be used in various forms including stretchedfilms, unstretched films, sheets, fibers, tubular articles andencapsulants for electronic parts.

ADVANTAGES OF THE INVENTION

The resin compositions and molded or formed articles according to thepresent invention excel in mechanical properties as well as theresistance to heat, chemicals, wet heat and oils. For instance, if suchcompositions are molded or formed into food containers, it is thenpossible to obtain containers which can be used for cooking needingextended heating in electronic oven ranges, etc. According to thepresent invention, it is also possible to obtain from thin- torelatively thick-walled formed articles in the form ofstretched/unstretched films, sheets, fibers, tubular articles andencapsulants for electronic parts, by way of example. In addition,fillers may freely be incorporated into the present compositions andarticles, and conventional melt processing techniques may suitably beapplied for molding or forming.

EMBODIMENTS OF THE INVENTION

The present invention will be described specifically with reference tothe following Examples and Experimental Examples. It should however beborne in mind that the scope of the present invention is not limited tothe following Examples.

Synthesis of the PAS Synthesis of poly(p-phenylene sulfide) (PPPS)Synthesis Experiment 1

A titanium-lined polymerization reactor was charged with 370 kg ofhydrated sodium sulfide (water content: 53.6 wt %) and 800 kg ofN-methylpyrrolidone (NMP), which were slowly heated to 203° C. in anitrogen gas atmosphere, while distilling off a solution of NMPcontaining 144 kg of water. Subsequently, 4 kg of water were added tothe reactor, and a mixed solution of 320 kg of p-dichlorobenzene (PDCB)with 280 kg of NMP was then supplied to the reactor. Polymerizationreaction was carried out for 4 hours at 220° C. Further, 110 kg of waterwere added (under pressure) to the reactor, and the contents were heatedto 260° C. to continue polymerization reaction for 5 hours. Aftercooling, the reaction solution was sieved through a 0.1-mm mesh screento separate a granular polymer, which was then washed with methanol andwater. Next, the polymer was treated in a 2% aqueous solution ofammonium chloride at 40° C. for 30 minutes, followed by water washingand drying. The polymer was found to have a melt viscosity of 1410 poise(as measured at 310° C. and a shear rate of 1200/sec) and an η_(inh) of0.33 dl/g (as measured at a polymer concentration of 0.4 g/dl and atemperature of 208° C.).

Synthesis Experiment 2

A titanium-lined polymerization reactor was charged with 11.0 kg of NMPand 3.39 kg of hydrated sodium sulfide (water content: 53.6 wt. %),which were gradually heated to 200° C. in a nitrogen gas atmosphere todistill off water and some NMP (the content of water remained in thereactor being 0.47 kg).

Next, 2.955 kg of PDCB dissolved in 3.0 kg of NMP was added into thereactor, and was held at 215° C. for 3 hours. Further, 0.97 kg of waterwas added under pressure into the reactor and polymerization wascontinued at 255° C. for 0.5 hour. By florescent X-ray analysis, theformed p-phenylene sulfide polymer was found to have a mean degree ofpolymerization of 190.

A 20-liter pressure-resistant titanium-lined polymerization reactor wascharged with 2.2 kg of NMP and 0.68 kg of hydrated sodium sulfide (watercontent: 53.6 wt. %), which was slowly heated to 200° C. in a nitrogengas atmosphere to distill off water and some NMP (the content of waterremained in the reactor being 0.10 kg). m-Dichlorobenzene (0.59 kg) wasmixed with 0.6 kg of NMP. The NMP solution of m-dichlorobenzene, 80% byweight of the total amount of the said reaction mixture, 0.38 kg ofwater was charged into the reactor and polymerization was carried out at255° C. for 2 hours. After the reaction, the obtained reaction productwas diluted about twice with NMP and filtered to separate a solidmatter, which was washed four times with hot water and then dried at 80°C. to obtain a polymer (p-phenylene sulfide block copolymer with themean degree of polymerization of ##STR19## blocks being 190).

Infrared spectrophotometric analysis of the composition of the obtainedpolymer indicated that it consisted of 82 mol % of the ##STR20##component and 18 mol % of the ##STR21## component. The η_(inh) and meltviscosity were 0.24 dl/g (at a polymer concentration of 0.4 g/dl and atemperature of 208° C.) and 580 poise (at 310° C. and a shear rate of1200/sec), respectively, while the Tg and Tm were 73° C. and 278° C.,respectively.

Tg and Tm were measured on a differential scanning calorimeter.

Synthesis of the PTK Synthesis Experiment 3 Melt-Stable PTK

A titanium-lined polymerization reactor was charged with 90 moles of4,4'-dichlorobenzophenone (manufactured by Ihara Chemical Industry Co.,Ltd.), 90 moles of hydrated sodium sulfide (water content: 53.6 wt. %and manufactured by Sankyo Kasei Co., Ltd.) and 90 kg of NMP (watercontent/NMP=5.0 moles/kg). After the reactor being purged with nitrogengas, the mixture was heated from room temperature to 240° C. over 1.5hours and then maintained for 0.9 hour. While a mixture of 5.0 moles of4,4'-dichlorobenzophenone, 20 kg of NMP and 100 moles of water wascharged into the reactor under pressure, the reaction mixture was heatedto 260° C. over 0.5 hour and maintained for further 1.0 hour forreaction.

The polymerization reactor was cooled, and the reaction slurry wascharged into about 200 liters of acetone and filter out a polymer, whichwas then washed three times each with acetone and water, each in threeportions. Acetone and water were removed to obtain the polymer in a wetstate, which was in turn dried under reduced pressure at 70° C. for 12hours, thereby obtaining Polymer A as an ivory powder.

Synthesis Experiment 4 Conventional PTK

A polymerization reactor made of SUS 316 was charged with 1.0 mole ofsodium sulfide trihydrate, 800 ml of NMP and 1.0 g of sodium hydroxide,and the mixture solution was heated to 210° C. to distill off 42 g ofwater solution containing 3 g of NMP and were thereafter cooled down toabout 45° C. Under vigorous stirring, 1.0 mole of4,4'-difluorobenzophenone and 0.033 mole of sodium sulfite were addedinto the reactor (water content/NMP=0.9 mole/kg). The reaction systemwas pressurized to 5 atm with nitrogen gas, and was maintained at 250°C. for 4 hours for polymerization. After the reaction, thepolymerization reactor was cooled down to 100° C., and the reactionmixture was taken out. The resulting polymer was separated from thatmixture, and was repeatedly washed with hot water and acetone. Aftersufficient wash of the polymer, it was fully dried to obtain Polymer B-1as a yellowish brown powder.

Synthesis Experiment 5 Preparation of PTK Described in U.S. Pat. No.4,690,972

A polymerization reactor made of SUS 316 was charged with 2.08 moles ofsodium hydrosulfide hydrate (water content: 31.9 wt. %), 2 moles ofsodium hydroxide and 1200 ml of NMP, which were heated to 205° C. in anitrogen gas stream to distill off 33.9 g of a liquid containing 5.6 g(5.5 ml) of NMP.

Thereafter, the reaction system was cooled down to 120° C., and a mixedsolution of 2 moles of 4,4'-dichlorobenzophenone and 1205.5 ml of NMPwas added thereto (water content/NMP=0.6 mole/kg). Polymerization wascarried out at 265° C. for 3.5 hours under pressure in the presence ofnitrogen.

After the reaction, the reaction slurry was poured into water andrepeatedly washed with water and acetone. Subsequent drying gave PolymerB-2 as a brown powder.

Measurement of Melting Point

The melting point, Tm was measured in the following manner. About 10 mgof PTK (powder) was first weighed. On a differential scanningcalorimeter (Model TC10A manufactured Mettler Company), the sample washeld at 50° C. for 5 minutes in an inert gas atmosphere and then heatedat a rate of 10° C./min to determine its melting point.

As a result, Polymer A was found to have Tm of 360° C. Polymers B-1 andB-2 were found to have their Tm's ranging from 350° to 380° C.

Measurement of Residual Melt Crystallization Enthalpy and MeltCrystallization Temperature

Residual melt crystallization enthalpy, ΔHmc (420° C./10 min) and meltcrystallization temperature, Tmc (420° C./10 min) were measured as anindex of melt stability. Namely, about 10 mg of PTK (powder) was firstweighed. The sample was held at 50° C. for 5 minutes in an inert gasatmosphere, heated to 420° C. at a rate of 75° C./min, held at thattemperature for 10 minutes, and was cooled down at a rate of 10° C./minon a differential scanning calorimeter, whereby ΔHmc (420° C./10 min)and Tmc (420° C./10 min) were measured.

As a result, Polymer A was found to show a ΔHmc of 59 (J/g) and a Tmc of306° C. Both Polymers B-1 and B-2 were zero in terms of ΔHmc, and wereunmeasurable in terms of Tmc.

Measurement of Density and Solution Viscosity

Density was measured as an index of crystallinity. First of all, PTK(powder) was placed between two polyamide films ("Kapton"--trade mark--manufactured by Du Pont de Nemours & Co., Inc.). It was preheated at385° C. for 2 minutes and pressed at that temperature for 0.5 minute forshaping with the use of a hot press. The product was quenched to preparean amorphous sheet of about 0.15 mm in thickness. One part of theamorphous sheet was used directly as a sample, while another part wasannealed at 280° C. for 30 minutes to prepare an annealed sample havingan increased crystallinity. The density was measured at 25° C. by meansof a density gradient tube (lithium bromide/water).

With respect to each PTK, the solution viscosity (reduced viscosity,η_(red)) was measured as an index of its molecular weight. Morespecifically, each PTK sample was dissolved in 98 wt. % sulfuric acid toa polymer concentration of 0.5 g/dl, and was measured by means of aUbbellohde viscometer. As a result, Polymer A was found to show adensity (g/cm³) of 1.30 for the amorphous sample and 1.35 for theannealed sample and have a reduced viscosity of 0.61 dl/g. Both PolymersB-1 and B-2 underwent local foaming during melt processing and showedvariations in density ranging from 1.28 to 1.30 for the amorphoussamples and 1.30 to 1.31 for the annealed samples.

It is found from the results that Polymer A, that is the melt-stable PTKaccording to the present invention, is of high density and highcrystallinity and shows a density of 1.34 g/cm³ or higher for theannealed sample, while Polymers B-1 and B-2, that are PTK according tothe prior art, undergo crosslinking accompanied by local foaming duringthe melt processing, so that the density and crystallinity of theobtained sheets are limited to low levels.

Measurement of Crystallization Rate

The half-crystallization time, τ_(1/2) was determined according to theknown method [e.g., "Kobunshi Kagaku", 25, 155 (1968)] with the use ofDSC 7 manufactured by Perkin Elmer Co., Ltd.

The conditions for measurement are as follows.

About five milligrams of a quenched pressed-sheet test piece of eachsample was melted at 340° C. for 1 minute in a nitrogen gas stream, andwas thereafter rapidly cooled down to the predetermined crystallizationtemperature, at which an isothermal crystallization curve is obtained.The time, τ_(1/2) needed for the crystallization of a half of acrystallizable component is calculated using that curve.

Shorter half-crystallization time, τ_(1/2) means a highercrystallization rate.

Measurement of Spherulite Size

A sheet obtained by heating and melting a polymer or polymer blend underpressure and quenching it was melted at 340° C. for 1 minute, and wasthereafter rapidly cooled down to 250° C., at which it was isothermallycrystallized. At the time when growing spherulites collided with eachother, the size of the spherulites was measured under a polarizedmicroscope equipped with a heater/cooler.

EXAMPLES 1-3

Using a tumbler blender, the PTK obtained in Synthesis Experiment 3 inthe form of powder and glass fibers (GF) of chopped strands of 3 mm inlength and 13 μm in diameter were mixed with the PPPS obtained inSynthesis Experiment 1, each in an amount of 100 parts by weight, in theproportions specified in Table 1, thereby obtaining blends.

Each blend was supplied to a twin-screw extruder including a cylinderhaving a diameter of 35 mm and a length of 1 m and equipped with anozzle having three holes whose diameters were 4 mm each and wasmelt-extruded in a strand form at a cylinder temperature of 320° C. fora residence time in the cylinder of about 3 minutes. The strands werequenched and cut to obtain strand-cut pellets.

Each pellet sample was supplied to an injection molding machine (havinga vent and working at a mold clamping pressure of 75 tons) equipped witha mold for food contains, and was injection-molded under the conditionsof a cylinder temperature of 320° C., a mold temperature of 150° C., aninjection holding pressure of 1000 kg/cm², an injection molding cycle ofabout 40 seconds and a residence time in the cylinder of about 1 minute,thereby obtaining a food container, which was then annealed at 200° C.for 4 hours. The food containers were found to have a thickness of 1 mm.

In order to measure the physical properties of the molded articles, themold was replaced by a mold for the preparation of test pieces to bemeasured as regards their physical properties, and the test pieces(annealed pieces) were prepared from the pellets in the same manner asdescribed in connection with the preparation of the food containers.

The blend formulation and physical properties of the test pieces thusmolded are set out in Table 1.

A beef paste was filled in each of the thus-prepared food containers,and was cooked in an electronic oven range while controlling a heatervoltage in such a manner that the upper and bottom temperatures of thecontainer ranged from about 220° to 230° C. After 25 minutes, thecontainer was removed from the oven to observe its state of distortion.The results are set out in Table 1.

COMPARATIVE EXAMPLES 1-2

Molded articles were obtained in a similar manner as above, except thatthe PPPS and PTK respectively obtained in Synthesis Experiments 1 and 3were independently used as the resins, and glass fibers were blendedtogether in the proportions specified in Table 1. It should be borne inmind, however, that the PTK was pelletized by melt-extruding it in astrand form at a cylinder temperature of 370° to 380° C. for about 3minutes of a residence time in the cylinder, followed by quenching andcutting, and that the PTK was molded into food containers by supplyingit to an injection molding machine equipped with the aforesaid mold forfood containers and injection-molding it under the molding conditions ofa cylinder temperature of 375° C., a mold temperature of 180° C., aninjection holding pressure of 1000 kg/cm², an injection molding cycle ofabout 40 seconds and a residence time in the cylinder of about 1 minute.The molded containers were annealed at 280° C. for 4 hours.

COMPARATIVE EXAMPLES 3-4

Added to 100 parts by weight of the PPPS obtained in SynthesisExperiment 1 were 10 parts by weight of the PTK obtained in a similarmanner as described in Synthesis Experiment 4 and, as was the case withExample 2, 74 parts by weight of glass fibers were added to the productto obtain a composition. A similar composition was separately obtainedwith 10 parts by weight of the PTK obtained in a similar manner asdescribed in Synthesis Experiment 5.

Obtained from the compositions were pellets, test pieces and moldedarticles (containers) in a similar manner as described in the foregoingexamples. The obtained brown pellets were all found to containconsiderable bubbles and show noticeable variations in color.

The containers underwent no distortion, but was inferior inreleasability to the molded article of Example 2. The physicalproperties of the products obtained form these compositions are also setout in Table 1.

EXAMPLE 4

One hundred parts by weight of the PPPS obtained in Synthesis Experiment2 and 1.0 part by weight of calcium carbonate were uniformly blendedtogether by means of a Henschel mixer. Then, 5 parts by weight of thePTKf obtained by Synthesis Experiment 3 and glass fibers (GF) of choppedstrands having a length of 3 mm and a diameter of 13 μm were added toand mixed with the blend by means of a tumbler blender to obtain ablend. A molded article was obtained from this blend in the same manneras described in the foregoing examples.

The physical properties of the molded article are set out in Table 1.

From Table 1, it is evident that the heat-resistant containers accordingto the examples of the present invention excel in not only heatresistance but also mechanical strength. As will be clearly understoodfrom the fact that the half-crystallization time, τ_(1/2) is short, thecrystallization rate of the resin compositions according to the presentinvention are so high that their moldability are improved.

                                      TABLE 1                                     __________________________________________________________________________                  Example 1                                                                            Example 2                                                                             Example 3                                                                            Example 4                                 __________________________________________________________________________    Blending formulation                                                          PPPS                                                                          (kind)        Syn. Exp. 1                                                                          Syn. Exp. 1                                                                           Syn. Exp. 1                                                                          Syn. Exp. 2                               (wt. parts)   100    100     100    100                                       PTK                                                                           (kind)        Syn. Exp. 3                                                                          Syn. Exp. 3                                                                           Syn. Exp. 3                                                                          Syn. Exp. 3                               (wt. parts)   0.1     10      24     5                                        Glass fibers* (wt. parts)                                                                    67     74      83     56                                       CaCO.sub.3 ** (wt. parts)                                                                    0      0       0      1                                        Properties of test pieces                                                     Heat distortion temp. (°C.)                                                          270    272     275    260                                       ASTM D-648                                                                    Load: 18.6 kg/cm.sup.2                                                        Flexural strength at 200° C.                                                         5.5    6.0     6.5    4.5                                       (kg/mm.sup.2)                                                                 Flexural strength at 200° C.                                                         320    335     350    312                                       (kg/mm.sup.2)                                                                 Heat distortion of container                                                                No distortion                                                                        No distortion                                                                         No distortion                                                                        No distortion                             250° C. τ1/2 (sec)                                                               100     26      25     68                                       __________________________________________________________________________                  Comp. Ex. 1                                                                          Comp. Ex. 2                                                                           Comp. Ex. 3                                                                          Comp. Ex. 4                               __________________________________________________________________________    Blending formulation                                                          PPPS                                                                          (kind)        Syn. Exp. 1    Syn. Exp. 1                                                                          Syn. Exp. 1                               (wt. parts)   100     0      100    100                                       PTK                                                                           (kind)               Syn. Exp. 3                                                                           Syn. Exp. 4                                                                          Syn. Exp. 5                               (wt. parts)    0     100      10     10                                       Glass fibers* (wt. parts)                                                                    67     67      74     74                                       CaCO.sub.3 ** (wt. parts)                                                                    0      0       0      0                                        Properties of test pieces                                                     Heat distortion temp. (°C.)                                                          270     340<   271    271                                       ASTM D-648                                                                    Load: 18.6 kg/cm.sup.2                                                        Flexural strength at 200° C.                                                         5.5     11     5.7    5.8                                       (kg/mm.sup.2)                                                                 Flexural strength at 200° C.                                                         320    680     330    332                                       (kg/mm.sup.2)                                                                 Heat distortion of container                                                                No distortion                                                                        No distortion                                                                         No distortion                                                                        No distortion                             250° C. τ1/2 (sec)                                                               185    Unmeasurable                                                                           41     43                                       __________________________________________________________________________     *Glass fibers: "03T717/p", trade name; 3 mm chopped strands; product of       Nippon Electric Glass Co., Ltd.                                               **CaCO.sub.3 : "CCR", trade name; product of Shiraishi Calcium Kaisha,        Ltd.                                                                     

EXAMPLE 5

A polymerization reactor was charged with 42.4 kg of hydrated sodiumsulfide (water content: 53.6 wt. %) and 100 kg of NMP. The mixture washeated to about 190° C. to distill off a solution of NMP containing 15kg of water. Then, 40.9 kg of p-dichlorobenzene was charged, followed bypolymerization at 220° C. for 5 hours. Next, 7.7 kg of water was chargedinto the reactor, and the temperature was increased to 260° C., followedby polymerization for 3 hours.

A polymer was sieved out of the reaction solution, washed with methanol,water, 2% ammonium chloride and water respectively and dried to obtainPPPS, which was found to have a logarithmic viscosity number of 0.12dl/g.

One part by weight of the PTK obtained in Synthesis Experiment 3 wasadded to and mixed with 100 parts by weight of the PPPS in a Henschelmixer, and the mixture was extruded into pellets through an extruder("BT-30", trade name; manufactured by Plavor Co., Ltd.).

The results of examination of the compositions consisting of the PPPSalone and the PPPS with the PTK are as set out in Table 2.

                  TABLE 2                                                         ______________________________________                                        Blending formulation                                                                            τ1/2 at                                                                              Spherulite                                       (pars by weight)  250° C. (sec)                                                                     size (μm)                                     ______________________________________                                        Comp. PPPS alone      610        170                                          Ex. 3                                                                         Ex. 5 PPPS 100/PTK 1   12         8                                           ______________________________________                                    

As shown in Table 2, the composition of the present invention had a highcrystallization rate and a small spherulite size, and was uniform.

We claim:
 1. A method for the production of a heat-resistant article,comprising injection-molding a resin composition using a cylindertemperature of 270° to 400° C., a mold temperature of 50° to 250° C., aninjection holding pressure of 10 to 5000 kg/cm² and an injection moldingcycle of 1 to 600 seconds and optionally, annealing the thus-moldedproduct at 120° to 250° C. for 10 to 600 minutes, said resin compositionformed by mixing:(A) 100 parts by weight of a poly(arylene sulfide) of asubstantially linear structure containing 50% by weight or higher ofrecurring units of the formula: ##STR22## and having a logarithmicviscosity number of 0.1 to 1.0 dl/g in a 1-chloronaphthalene solution ata polymer solution of 0.4 g/dl and a temperature of 208° C.; (B) from alower limit of 0.01 to an upper limit of less than 25 parts by weight ofa melt-stable poly(arylene thioether-ketone) having predominantrecurring units of the formula: ##STR23## wherein the --CO-- and --S--are inthe para position to each other, and having the following physicalproperties (a)-(c):(a) melting point, Tm being 310°-380° C.; (b)residual melt crystallization enthalpy, ΔHmc (420° C./10 min) being atleast 10 J/g, and melt crystallization temperature, Tmc (420° C./10 min)being at least 210° C., wherein ΔHmc (420° C./10 min) and Tmc (420°C./10 min) are determined by a differential scanning calorimeter at acooling rate of 10° C./min after the poly(arylene thioether-ketone) isheld at 50° C. for 5 minutes in an inert gas atmosphere, heated to 420°C. at a rate of 75° C./min, and then held at 420° C. for 10 minutes; and(c) reduced viscosity being 0.2 to 2 dl/g as determined by viscositymeasurement at 25° C. and a polymer concentration of 0.5 g/dl in 98 wt.% sulfuric acid; and (C) at least one filler selectedf from the groupconsisting of fibrous fillers and inorganic nonfibrous fillers in aproportion of 0 to 400 parts by weight per 100 parts by weight of saidpoly(arylene sulfide) and said poly(arylene thioether-ketone).
 2. Themethod as claimed in claim 1, wherein said heat-resistant molded articlehas the following physical properties (a) and (b):(a) heat distortiontemperature being at least 220° C. under a load of 18.6 kg/cm², and (b)flexural strength being at least 2 kg/mm² at 200° C., or flexuralmodulus being at least 100 kg/mm² at 200° C.
 3. The method as claimed inclaim 1, wherein said poly(arylene sulfide) is a block copolymerconsisting of 70 to 95 mol % of recurring units of the formula:##STR24## and 5 to 30 mol % of recurring units of the formula: ##STR25##4. The method as claimed in claim 1, wherein the density of saidpoly(arylene thioether-ketone) is at least 1.34 g/cm³ at 25° C. whenannealed at 280° C. for 30 minutes.
 5. The method as claimed in claim 1,wherein said poly(arylene thioether-ketone) is an uncured polymer. 6.The method as claimed in claim 1, wherein said heat-resistant moldedarticle is a heat-resistant food container.